John Bird (astronomer)

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John Bird (* 1709 in County Durham , † March 31, 1776 in London ) was an English astronomer and manufacturer of scientific instruments.

He first worked for the instrument maker Jonathan Sisson and later became its partner. Both made navigational instruments for merchant ships on the recommendation of the Royal Society .

6-foot quadrant of the wall by Bird 1756, Göttingen observatory. With him between 1756 and 1758 Tobias Mayer determined 1000 star locations

Bird was very successful in the further development of astronomical instruments and started his own business in 1744. The geodesist Jeremiah Dixon also used some measuring instruments . A significant order was a 6-foot quadrant of the wall for the Royal Greenwich Observatory , which was delivered in 1750. Like the twin instrument built in 1756 for the Göttingen observatory , it had a 3-inch lens with a focal length of around 2 meters and a newly designed thread-net eyepiece. Observatories in France, Spain and Russia also ordered such instruments.

Since astrometry had become the main task of many observatories, Bird developed an even larger wall quadrant for Greenwich and for the Berlin observatory (1768) around 1765 . He had an achromatic 81 mm lens from John Dollond with a focal length of 2.7 meters and a resolution of better than 2 ". The pitch circle was designed as a double circle (two concentric scales) to increase angular accuracy . The eyepiece micrometer was adjustable and the telescope bend Mechanically compensated Instruments of the same design were given to the Radcliffe Observatory in Oxford in 1772 and the Mannheim observatory in 1776. The latter is still in good working order.

When the Greenwich astronomer James Bradley of "Length Commission" ( Board of Longitude ) the high quality of the quadrant reported this Bird commissioned by an impressive £ 500 to pass on his knowledge to selected apprentices and to document the working methods exactly. This resulted in the works The Method of Dividing Mathematical Instruments (1767) and The Method of Constructing Mural Quadrants (1768), for which Bradley's successor Nevil Maskelyne wrote the foreword.

Bird made two yard gauges in 1758 and 1760 , but they were destroyed in the parliamentary fire in 1834. With one of his astronomical quadrants, James Cook observed the passage of Venus in Tahiti in June 1769.

Thomas Pynchon set Birds Instruments a literary monument in his 1995 novel Mason & Dixon about measuring the US borders.

Web links

Individual evidence

  1. ↑ JSSchlimmer: The wall quadrant of the Mannheim observatory by J. Bird, 1775. In: epsilon-lyrae.de. Retrieved January 18, 2009 .
personal data
SURNAME Bird, John
BRIEF DESCRIPTION English astronomer
DATE OF BIRTH 1709
PLACE OF BIRTH County Durham
DATE OF DEATH March 31, 1776
Place of death London